Quake 4, a DVD-ROM in English by ID and Raven Software for Activision, distributed with a 28-page English-language user's manual by Hed Artzi Multimedia, requires Windows XP and a 2 gigahertz Pentium IV PC, for ages 18 through adult. Technical rating: ****1/2 stars Moral rating: 0 stars Try not to eat lunch before launching this savage first-person shooter game: It begins with bodies of marines floating after the explosion of their spacecraft, with holes instead of eyes and intestines visible. You can skip the video introduction when you subsequently return to the game, whose play is somewhat less ghoulish - but not much - and then resume your normal dietary activities if you have the stomach for it. Yes, Quake 4 - which is run on the same graphics engine of the much-vaunted Doom 3 - has a superb, realistic look with varied indoor and outdoor environments and human faces whose visual quality is among the best in gaming. But the faint-hearted (like me) would probably prefer a little fuzziness and less-vivid images; yet I suppose that if you really want to play it, you are not the lily-livered type. At least the enemies you're shooting at are aliens. I do worry, however, that plenty of younger teenagers will be playing the game behind their parents' backs, even though officially it is only for those 18 and over. Although there was a little-noted Quake 3 (4 is the first of the series that I have seen), the new game is a continuation of Quake 2, when humanity in the form of American marines has been waging an interminable war with the Strogg, an alien race that invaded Earth in the middle of this century. Residents of the planet Stroggos, they use the bodies of their foes as raw materials to manufacture new soldiers to fill the ranks, a rather efficient but unappetizing talent. Man counterattacked on the Stroggs' home ground, and many marines were lost, but one survived and killed Makron, their leader. But the Stroggs bounced back, and the struggle continues in Quake 4, where you play Matthew Kane - another marine who takes orders and is member of a squad rather than an officer who gives orders. Kane hardly says a word in the whole game, but his comrades are quite talkative. They are not mindless team members, however, as the computer's artificial intelligence gives them enough abilities to fight even before Kane arrives on the scene - but the Stroggs themselves lack such AI and often stand transfixed and shoot without seeking cover. Your weapons include the standard marine-issued energy pistol, but this proves quite useless in battle. You'll also have an eight-round shotgun for close-range combat, plus a nail gun, hyperblaster, rocket launcher, lightning gun and grenade launcher. But most of the time you'll probably shoot your trusty machine gun, which combines automatic fire 40 rounds at a time with a single-shot scoped mode; press the built-in flashlight key to light up the darkness when necessary. On Stroggos, you can pick up locally developed weapons to give your enemy a taste of their own medicine. You can take the controls of a Hovertank and Walker, each of which has its own weapons. You'll spend most of your time rushing from one place to another (often via elevators) and shooting aggressively, but you also must be on the defensive to avoid missiles and bullets aimed at you by insect-like creatures. The fast-paced mutliplayer mode pits combatants against each other in a frenetic arena, putting you against opponents in cyberspace through a maximum of five game modes, including a death match and capture the flag. Pick up yellow crosses, which boost your health by 25 points, and gold ones by double that; green health packs can raise your health above 100 points, while blue "mega health" packs give you up to a maximum of 200. Medics heal you and engineers repair your damaged shiny metal armor (which is available in three strengths), while "haste" increases your run speed and fire rate, "regeneration" restores 15 health points per second when your level falls below 100 and "invisibility" makes you harder to see for a short time. When you run out of points, you're dead and have to start again. After excreting plenty of adrenaline for the 12 to 15 hours that it takes to play Quake 4, you are likely to feel exhilarated, or exhausted, or sick to your stomach, or so addicted that you'll want to start all over again.